End mill



-' June 5, 1945. I DETTMER 2,377,329

END MILL Filed April 1, 1944 INVENTOR. (1W 8.0M BY v Patented June 5, 1945 END MILL Alfred B. Dettmer, Cleveland, Ohio, assignor to The Weldon Tool Company, a corporation of Ohio Application April 1, 1944, Serial No. 529,049 8 Claims. (01. 294103) My invention relates generally to milling tools and more particularly to fluted end mills and the I like.

An object of my invention is to provide an end mill having flutes disposed to out towards the end of the mill and having end cutting tips dis" posed to cut away from the end of the mill.

Another object of my invention is the provision, in an end mill having a plurality of flutes spiraling toward the end of the mill, of cutting tips which cut in the direction opposite to the direction cut by the flutes.

Another object of my invention is the provision of an end mill having longitudinal flutes producing an endward cutting action, and having an end portion of non-clogging cutting edges.

Another object of my invention is to provide an end mill having a plurality of flutes spiraling in a direction opposite the direction in which the end mill is disposed to rotate, and having a cuttin end with an angle of rake opposite to the angle of the spiral flutes.

Other objects and a fuller understanding of my invention may be had by referring to the following description and claims taken in conjunction with the accompanying drawing, in which:

Figure 1 is a longitudinal view of a type of end mill embodying the features of my invention;

Figure 2 is a longitudinal view of a type of end mill embodying the features of my invention shown at right angles to Figure 1;

Figure 3 is a perspective view of the end of an end mill embodying the features of my invention; and

Figure 4 is a view of an mill embodying the features of my invention shown in a cutting position on a work piece.

With reference to Figure 1 and Figure 2 of the drawing, I illustrate a type of end mill ID embodying the features of my invention and comprising generally a shank portion I I and a fluted portion I2 having end cutting tips I6 and I1. The end mill I is disposed to rotate about an axis in the direction indicated by the directional arrow I3. The shank portion II has flat surfaces 30 and 3| to facilitate the holding of the end mill ID in a driving device. The fluted portion I2 has two flutes I4 and I5 thereon. The flutes I4 and I3 on the fluted portion I2 spiral endwardly away from the shank portion II in a direction opposite that of the direction of rotation of the mill Ill. At the end of the fluted portion I2 are two fluted cutting tips I6 and H which spiral about the fluted portion I2 in a direction opposite the direction which the flutes I4 and I5 spiral about the fluted portion I2. 'I'he'tips I6 and Il extend a short distance from the end rearwardly toward the shank portion II and are axially co-extensive with the flutes I4 and I 5 over part of their length.

As shown in Figures 1 and 2 of the illustration, the flutes I4 and I5 are integral with the end mill and are extended in a spiral manner along the fluted portion I2. It is noted in Figure'4 that the spiral flutes I4 and I5 terminate a short distance rearwardly of the extreme end of the mill Ill. However. the flutes I4 and I5 are extended far enough endwardly that they become axially coextensive with the cutting tips IB and I I. In

Figure 3 the butt ends of flutes I4 and I5 are shown on surfaces I9 and I8 respectively. Each flute, such as flute I4, has an undercut side 32 and'a backing side 33 which converge to form a longitudinal cutting edge 23. The flute I5 has a cutting edge 22 formed similarly to cutting edge 23 of flute I4. The backing side 33 for both of the flutes has a first cutting clearance 26 generally termed the first backoif clearance and a second cutting clearance 34 generally termed the second backoif clearance. The combination of first and secondbackoif is called a double backofl clearance. The contour of the undercut side .32 is arcuate so that the undercut side 32 extends outwardly from the valley between the flutes in a curve to the longitudinal surface 34.

As the mill I0 rotates in the direction indicated by directional arrow I3, the cutting edges 22 and 23 of the flutes I5 and I4 produce a downward slicing cutting action on the material being cut. The downward cutting action is highly beneficial because it does not chip or tear the corner of the work piece cut by the tool, such, for example, as the corner 45 of the work piece 46, see Figure 4. However, it is difficult to form satisfactory end cutting edges on downward cutting flutes such as those described herebefore. Therefore, at the end of the mill I B furthermost removed from the drlving engagement shank portion II, I provide the cutting tips-I6 and H. The structure and position of the cutting tips I6 and I! can be seen in Figure 3 of the drawing. As shown in Figure 3, the cutting tips I6 and I! have longitudinal cutting edges 25 and 24. The cutting edges 25 and 24 have radial diameters equal to the radial diameters of cutting edges 22 and 23 of flutes I4 and I5. The cutting edges 25 and 24 of tips I6 and I! also have a double backoii clearance as herebefore described. The surfaces of the double backoif clearance of the longitudinal cutting edges 25 and 24 of cutting tips I6 and I! are shown in Figure 3 by reference-characters 40 and M.

50 disposed parallel to the axis of rotation of the end mill providing substantially a zero rake angle or the raking surfaces!!! may "incline'ata predetermined rake angle with the axis of the mill I0. I illustrate the raking surface 50 of the cutting tips I6 and H as lbeinginclined orspiraling at a rake angle of substantially with the axis of rotation of the end mill. film-operation ofimy endmill will lie-better ,understood by referring :to Figure 4 of :the :drawing in which the directional {line 13 indicates the (direction .of. rotation .of ;a-;type :of an end-mill Ill conforming to mydm'ention. As-rotation of .the end mill 10 takes place, the idagitudinalcutting-edge 23 of the spiral flute -14 rensageswm top corner v45 of, the. material '46 being machined. Withcontinued rotationpf the :mill Al, the 2611i)- tingedge23 cuts downwardlyial'ong thersurface 41 of the material :46 asindicatedflby aadirectional arrow 4.8, whereby any SBVBICGChiDSzOl5Sh8ViQES are pushed downwardly toward the cutting "tips wand 11 of the end-mill i0. -The downward:cutting action described rplioduces :a clean sharp-corner, at 45,.instead of -.tearing=same which would be the case with anupward cutting 'actiomibb cause of the lack of a supporting mass :behind the corner. .-At the end of the mill, the longitudinal cutting edges .14 and of the cutting tips l6 and! laredisposed tosevenmaterialfmm the surface 41 of the material 146 at the inside corner 5|.

'I-helongitudinalcutting edges 124 and will cut on the surface i1 because the :edgesdl :and

25 have-a, circular diameter equal to the circular diameter of the longitudinal cutting edges .22 and 23 of spiral flutes l4 and 1:5. Furthermore, the surface 41 is disposed .to be continuous because the longitudinalicutting, edges .24 and .15 of the cutting tips l5 and. extend toward the :shank portion ll. far enough to overlap .or become axially co-extensive with .the longitudinal cutting edges 22 m: of thespiralflutes l4 and-J5,

The transverse cutting edges .36 and :31 of the cutting tips 1.6 and ;l1 :are disposed :to severmaterial from the bottom surface 49 of thematerial 46 and define agood sharpinside comer 5|. Any chips or shavings removed by the longitudinal cutting edges 2.4 and 25 or transverse edges .36 and 31 of the cutting tips iii-and l1;are.-.carried upwardly-on; the upward slanting or rakingsurfaces 5ll of the cutting tips l6 and 11.

The upward movement of the, :severed chips and, shavings described removes the .severed'mass from the end cutting edges .36 and :31 and thus prevents clogging .of the cutting tips. I

In my. invention the cutting. flutes of :thetool cut the work piece in.a,direction, towards theend of the mill. Accordingly,the-reactionofthe tool upon the spindle which holds theshank portion ll is such as to force the spindleawayfromthe work piece while ,at thesame time the reaction of the tool onthe .work piece is such-as to force the work piece against ;the -1bed plate or :fixture holding the work piece. The opposing reactions upon the spindle and the work piece prevent vibration which would otherwise occur if the cutting flutes cut the work piece in a direction away from the end of the tool.

Although I have described my invention with a certain degree of particularity, it is understood that the present disclosure has beenmade only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

I claim as my invention:

.1. An end mill comprising a driving engagement portion and a fluted portion having a cutting end, said end mill being adapted to rotate .in iii-certain:direction as viewed from the driving engagement portion, said fluted portion having spiral flutesbeginning at the driving engage- 111E111; portion and spiraling towards the cutting end in a direction opposite 'ito'that (of rotation of the end mill, said fluted portion having a pluralityof cutting tips .at .the cutting end thereof, said :flutes :and tips having longitudinal cutting edges extending therealong, and said tips also having transverse cutting edges at the cutting end thereof.

'2. An end .mill comprising a driving engagement portion and a, fluted portionihaving a.cutting end, .said end mill :adaptedto rotate in a certain direction-as viewed from the driving engagementportion, said fluted portion having spiralflutes Ebeginning 81713118 driving. .engage ment portion and spiraling towards the cutting end in a, direction apposite to that of the rotation of the end mill, said cutting endihaving a plurality of fluted cutting :tipsat the .end thereof disposed 'to spiral towards thejend of. the mill in a direction opposite to that .of the said spiral flutes, said flutes and tips having longitudinal cutting edges extending therealong and being a!- ially co-extensive over partfloftheirlength said tips also having transverse cutting edges at the cutting end thereof.

3. An end mill comprising a .drivingengagement portion and a fluted portion, said fluted portion having at least two flutes rannularly spaced by an angleof substantially 180 :and having a fluted cutting end, 'said end mill being adapted to rotate in a certain direction .as viewed from the driving engagement portion, said fluted portion having spiral flutes beginning at the driving =engagement portion and spiraling towards the cutting end in a direction opposite to that of the rotation of the end mill, said fluted cutting and having tips with longitudinal and transverse cutting edges and being disposed between .the said flutes and also being annularly spaced .from one another by an angle of substantially 180", the said longitudinal cutting edges .of the cuttin tips and of the flutes being axially coextensive over vpartof their length.

4. An end mill 'having'. in combination, a plurality of flutes with longitudinal cutting edges extending therealong and a plurality of fluted cutting tips located :at the end thereof, said flutes and cutting tips spiraling co-axially in opposite directions and said tips also having :transverse cutting .edgesat the cutting end thereof;

5. An end mill comprising :a driving engagement portion andafluted portion having a cut-- ting end, saidend mill being adapted to. rotate in a certain direction 18.8 viewedlfrom the drivin engagement portion, .said' fluted portion having portion and spiraling towards the cutting end in a direction opposite to that of the rotation of the end mill, said cutting end having a plurality of cutting tips at the end thereof, said flutes and tips having longitudinal cutting edges extending therealong and said tips also having transverse cutting edges, said tips and said flutes having longitudinal cutting edges disposed to cut in 0pposite axial directions.

6. An end mill adapted to rotate in a certain direction, and having flutes spiraling towards the cutting end in a direction opposite to that of the rotation of the end mill,- said end mill having a plurality of cutting tips at the cutting end thereof, and spiraling co-axially with, and in an opposite direction to that of the flutes and said tips also having transverse cutting edges at the cutting end thereof.

7. An end mill adapted to rotate in a certain direction, and having flutes spiraling towards the cutting end in a direction opposite to that of the rotation of the end mill, said end mill having a plurality of cutting tips at the cutting end thereof, and disposed between the flutes.

8. An end mill having a plurality of fiutes with longitudinal cutting edges spiraling toward the cutting end of the mill, and having a plurality of cutting tips disposed between the flutes at the cutting end of said mill, said tips having transverse cutting edges at the end thereof and having longitudinal cutting edges co-axial with the longitudinal cutting edges of said flutes ALFRED B. DETI'MER. 

